let btn = document.querySelector("#bt-submit")
btn.onclick = function () {


}

let username = document.querySelector("#username");
let user = document.querySelectorAll(".user");
user.forEach(function (v, i) {
    username.onblur = function () {
        if (username.value.length >= 6 && username.value.length <= 12) {
            v.style.display = "block";
        } else {

            v.style.display = "none";
        }
    }
})
// 验证用户名字6-12个字符